Oyster Mushroom

The Oyster Mushroom(Pleurotus ostreatus) is a sought after wild mushroom, and cultivated all over the world. I find this one often in the woods of Southern Ontario where I live. The Oyster mushroom can often be found as a cultivated mushroom in some grocery stores as well.

In the woods, it will be found growing on either dead standing, or fallen trees. I've only seen it on deciduous (hardwood) trees. It is reasonably straight forward to identify, but there other similarly shaped mushrooms growing on dead, standing trees.

Here is a quick start to identification, but please, do more research. One, it should have gills under the cap (top), not pores (gills look like sheets of paper spread apart, pores look like a bunch of straws from the end). It should have a stalk, even a very small one - some shelf mushrooms don't have what looks like a stalk. It should be white (they can be tan to brown, but those take more careful identification). Note: There are so many variations of the oyster mushroom, you could write a book just on them. Different shapes, colors, stem sizes, wavy edged, not wavy edged, and on and on.

They can look like the Clitocybe dealbata, but it is not found growing on logs or standing trees, it grows on lawns, fields, etc., so don't bother unless you see it growing on dead wood. Also, with the Clitocybe, the stem comes from the very center of the cap, not from the side of the cap like the Oyster mushroom usually does. If the stem does come from the center, leave it.

Eat only young specimens, cooked. Good in soups and stir-fry's. Since the flesh is thin and even in thickness, you can tear this one apart by hand. Again, I repeat, only start with a little if you don't know how you will react to it. Even though it is sold in stores, it does tend to make some people feel sick. This is one that makes me feel sick. I feel like I have the flu coming on. Let me tell you why you should always start with just a little of any new food.

Years ago, I found an amazing fresh crop of Oyster mushrooms on a fallen log in the center of an unpolluted, old growth deciduous forest. The log was a huge American Beech (Fagus grandifolia or Fagus americana), a good two feet in diameter in the truck many, many feet from the stump. The crop of mushrooms were young, white and covered the entire log. It was amazing to see. The year was around 1990, long before digital cameras, so sadly there are no pictures. I brought home a grocery bag full of choice specimens. I properly cooked them with onions and a little garlic and ate them with dry toast - a way I love to eat fresh mushrooms. I ate a small frying pan full. Within minutes of finishing them, I started to feel "odd". It started in my stomach area, then spread to the rest of my body. As time went on, I felt worse and worse. I wasn't sick to my stomach, I just felt like I was coming down with the flu in the very early stages, but worse than ever before. Nothing I could do would make me feel better. It took about 12 hours before I felt like I was starting to feel normal.

If I had eaten only a little amount to start, I wouldn't have felt so bad for so long. I learned my lesson, after that I always try any new food - especially mushrooms - with a very small amount.

You may want to try buying some in a grocery store, looking at it carefully, eating it and seeing how you react, then look for it in the wild. Don't buy them if they look beaten up and old. So often, they seem to have sat around too long in the store.

Cap Morphology: Cap is offset on the stem - the stem generally does not come from the center of the cap except when growing from the top of log (not common). The cap is irregular in shape and takes many forms and colors. Can be white, to tan, to light brown to dark brown, to a lilac-grey. Most often found with the margin of the cap turned down, but when fully mature the margin can be flat with the cap and very wavy and/or lobed. Cap shape can be convex, to flat, to concave to funnel shaped. Thickness of cap flesh is even and thin. Generally about 5-15 cm (2 to 6 inches) across

Spore Bearing Surface: Gills on the underside of the cap. Regardless of the color of the cap, the gills are white to a soft off-white, and on occasion a light tan or light pinkish.

Gill Attachment (how the Spore Bearing Surface is attached to the Stipe or Stem): Decurrent - the gills run down on to the stem

Spore print: White, though I have read there can be some with lilac tinted white spores.

Stipe (Stalk): Any one I have seen always a stalk that comes from the underside of the cap. It can be so short you don't notice it at first. David Arora in "Mushrooms Demystified" says that the stalk can be absent altogether. This doesn't surprise me, as everything about this mushroom is highly variable.

Habitat: Saprotrophic - found on dead wood. Mainly hardwood. It is my experience that though it can be found on most hardwoods, in Southwestern Ontario I find it most often on American Beech logs.

Notes: Though you can find a single one, it is most often found in large fruitings with mushrooms overlapping one another. Normally on the side of fallen logs or on standing dead trees. I have seen it coming from the top of logs, but this far less common.

The Oyster Mushroom(Pleurotus ostreatus) fruiting on standing dead wood. Just a note of precaution: standing dead trees can be dangerous to be under especially if there is wind as branches can suddenly (and silently) fall. (By: Jean-Pol GRANDMONT CC BY-SA 3.0)

Before Gathering and Eating any Wild Mushroom READ THE FOLLOWING:

This is a difficult subject to approach. I've been studying mushrooms in the wild for about 30 years and they often still surprise and confuse me when identifying.

The problem for a site like this, is that 100% correct identification is absolutely necessary, but hard to do for many mushrooms - even with years of experience, let alone a newcomer to the subject. Best to have someone with genuine expertise show you. If that is not possible, please do much research on the web or with books, preferably both. Do not trust a single source of information - EVER. I have found mistakes on the web, and have even corrected errors on Wikipedia myself. You need confirmation from multiple sources. If you are serious about the subject, one book I highly recommend is "Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi by David Arora". I bought the 1986 edition in 1987 and that is what got me started seriously learning about mushrooms. David Arora is from the west coast, but what he says about east coast mushrooms matches with my experience. There are pictures, and very well thought out step by step identification sequences.

Another book which is very good, and a great guide to carry with you on gathering expeditions is "The Audubon Society Field Guild to North American Mushrooms".

Before you gather anything, you must know the most dangerous mushroom of Eastern North American - it can mean your life if you don't. It is the Destroying Angel (Amanita bisporigera). There is another Destroying Angel on the west coast, the Amanita ocreata. Please take me seriously with this, the Destroying Angels not only kill, but they kill you slowly & painfully. Don't rely on taste, people who have eaten them said, before they died, they were very good tasting. I don't think there is anything, other than maybe the Water Hemlock plant, that kills with such pain and suffering. Look them up, read about them here - KNOW THEM.

I suggest only five mushrooms for the wild food gatherer & mushroom novice to start off with. The Chanterelle, Morel, Hericium, and the Sulphur Shelf and Giant Puffball. The Morel, and Giant Puffball can often be found in urban environments. The Chanterelle, Hericium, Morel and Sulphur Shelf in the woods. The Giant Puffball can be often found in grassy areas in the country. I have seen the Sulphur Shelf in the city on rare occasions on the side of dying trees. These five are relatively straight forward to identify correctly, and do not have deadly poisonous close look-alikes - although there may be similar looking mushrooms that could make you sick - very sick, so always take identification very seriously. Also, these are not mushrooms you can usually buy in the local grocery store. Until fairly recently, Morels could not be grown in artificial environments.

The Morel is a spring season mushroom, Chanterelle, Sulphur Shelf and Giant Puffball is a summer to fall mushroom, and the Hericium is a late summer to fall mushroom, so this gives a fairly large window of time to enjoy them. PLEASE take it very slowly, do a lot of research, look at many pictures, and learn how to identify the edible ones from mushrooms that look like them - STEP by STEP with each aspect of the mushroom. Remember, though I do my best to help you identify them, this is not a dedicated identification guide, you do need to learn more than I provide.

And by the way, be careful of what other people pick. Some people go by simple rules of identification that they have learned from others that don't hold up. They may have been lucky so far, but if you eat what others have picked, you had better hope they know what they are doing. Know what you are picking, don't use simple rules except for one: If you are not absolutely, 100% sure, with each and every aspect of the mushroom, do not eat it.

Spore Prints:

Learn to take a spore print. Put a mushroom cap on white and black paper, and cover with a cup or bowl and after a couple of hours take off the cup, carefully lift up the cap and you should see a spore print. The color of the spores is an important aspect of identification. Go to the spore print link, where you will see the black and white spore print paper image. Click on it, click again and print it. Here is a link directly to it. You can print the same image below:

Print this image to take your spore print on. (William Rafti of the William Rafti Institute CC BY-SA 3.0)

The next six images are the steps in taking a spore print:

This is an Agaricus bisporus that I'm using to demonstrate taking a spore print. This one still has a bit of the partial veil left on. It is the partial veil that makes the ring on the stem.

Next, you have to take off the stem so that the cap will sit flat on the paper. If the gills are "free" - don't touch the stem, you can usually break off the stem. If the gills touch the stem, (adnate, decurrent, etc.), you are best to cut the stem off carefully with a sharp, clean knife.

Set the cap, gills down, on a piece of paper. Put a drop or two of room temperature water on the cap, but not so much that it runs down to the paper. This helps the mushroom hydrate which helps it in the process of releasing the spores.

Cover with a glass or plastic container to keep it humid inside for the mushroom.

It can take as little as a couple of hours, to 12 hours in my experience to get a good print. If you have 12 hours, leave it. If you want to eat the mushroom sooner, take a look after a couple of hours. You may not get a nice looking print, but even a few spores should reveal their color.

This is a close up of the spore print. You can see the white lines where the gills were, and the spores on either side that dropped off. This is the brown for a spore print you would expect for an Agaricus bisporus.

Remember the mushroomer's motto: When in Doubt - Throw it Out. Even experts aren't sure sometimes, and will pass on eating a mushroom unless they are sure.

One more thing I will repeat over and over. When eating anything for the first time, only have a tiny amount to make sure you are not allergic to it. This is especially true for mushrooms. Every edible mushroom creates a reaction with some people. There are two choice edible mushrooms that I am allergic too. The Oyster mushroom makes me feel like I have the flu coming on, and the Boletus edulis makes me feel hot, I break into a sweat, and feel sick to my stomach.

If you think I'm being overly cautious, think about what I read years ago (I regrettably forget the source). There are two kinds of wild mushroom eaters: Brave ones and living ones.

Identification: When reading the description for the mushrooms, refer to the chart below for what those descriptions mean.

Creator of this chart: debivort. Used under GNU Free Documentation License. Full size and source of this image here.

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